1. Field of the Invention
The present invention relates to the detection of the insertion or noninsertion of a cassette in a recording or reproducing apparatus and, more particularly, to system control utilizing the detection of the insertion or noninsertion of a cassette, which system control is executed when dew condensation is detected in a VTR mechanism employing a slide chassis which enables relative movement between a rotary drum and a tape-shaped recording medium accommodated in the cassette.
2. Description of the Related Art
As is known to those skilled in the art, such a recording or reproducing apparatus is controlled by a method including the following major steps: detecting the presence or absence of dew condensation in the apparatus as well as the insertion or noninsertion of a cassette in the apparatus; and executing, if dew condensation is detected, the processing required to prevent a tape-shaped recording medium (hereinafter referred to as "tape") from being accidentally wound around or damaged by the rotary drum owing to the dew condensation. In general, this kind of control makes use of either one of the methods respectively shown in FIGS. 1(a) and 1(b) in flowchart form, each of which adopts a different method of detecting whether the cassette has been inserted in the apparatus. In both methods, Steps ST1 to ST3 execute the same processing. A cassette holder is moved from a position for insertion of the cassette in which the tape is accommodated to a position where the tape can be drawn out from the cassette, and the cassette holder is held at that position (ST1; the operation in Step ST1 is hereinafter called the operation of accommodating the cassette in the apparatus). When the cassette holder is held at the position, the presence or absence of dew condensation in the apparatus is detected (ST2). If the apparatus is not wet with dew condensation, loading means is actuated to cause the tape to form a predetermined path (ST3).
In the first method, the insertion or noninsertion of the cassette is detected through a detecting switch which is capable of coming into direct contact with the cassette. In the first method, as shown in FIG. 1(a), if the presence of dew condensation is detected in Step ST2, the insertion or noninsertion of the cassette is detected through the detecting switch (ST4). If no cassette has been inserted, a movable chassis is made to travel and the loading means is actuated (ST5) (The reason why Step ST5 is inserted is to minimize the size of the apparatus). If the cassette has been inserted, the loading means is not actuated and the process waits for an eject instruction (ST6). If the eject instruction is received, cassette ejection is performed (ST7).
In the second method shown in FIG. 1(b), the presence or absence of the tape is detected through a tape-end detecting sensor which is provided on a stationary chassis, and the presence or absence of the cassette is determined on the basis of the result of such detection. In this method, if the loading means is not actuated together with the movable chassis, it is impossible to perform detection of the presence or absence of the cassette. For this reason, if dew condensation is detected in Step ST2, no decision is made as to the presence or absence of the cassette, and the process waits for an eject instruction (ST11). Then, cassette ejection is performed (ST12).
The above-described first method is disadvantageous in that an exclusive detecting switch is needed. The second method has the disadvantage that the movable chassis is left projected with no cassette inserted and an exterior case of large size must be adopted if the amount of projection of the movable chassis is taken into account.